This invention concerns actuators for remotely controlling operative mechanisms. More particularly, the invention relates to an improved motorcycle throttle control unit for mounting on the handle bar for actuating the carburetor.
Throttle control units of the prior art have generally taken one of several forms. U.S. Pat. No. 2,796,773 to Wooler et al describes a twist-grip throttle control in which a Bowden cable has its inner wire core radially attached to a rotatable sleeve. Rotation of the sleeve causes the wire to wind around the sleeve to control the throttle. Such devices suffer the disadvantage that the sleeve is subject to wear and breakage and no positive stop or limit on twist-grip rotation is provided. It will also be appreciated that the cable in such devices will become stretched after numerous uses of the twist-grip control requiring frequent readjustment or replacement. Moreover, in such devices there is no means provided for securing the outer sheath of the cable in the control housing.
It has been recognized by the art that linear movement of the cable parallel to the axis of rotation of the twist-grip provides a more uniform movement of the cable, however, none of the prior art devices have successfully provided such construction.
U.S. Pat. No. 1,834,724 to Nisbet describes a twist-grip throttle control in which a Bowden cable has its inner core attached to a movable slide disposed on the periphery of the twist-grip housing. A portion of the slide engages a helical opening formed in a rotatable sleeve attached to the twist-grip. When the grip is rotated, the slide is moved linearly along the helical opening and parallel to the twist-grip axis to effect a movement of the inner core of the cable. It will be observed that such construction requires a great deal of twist-grip rotation to effect a small amount of linear movement of the slide. Moreover, the pitch of the helical opening must be made different for each type of carburetor with which it is to be used, since different carburetors will need differing amounts of cable "throw" to be fully actuated. No provision is made for securing the outer sheath of the cable in the housing.
Similarly, U.S. Pat. No. 3,522,745 to Milosevic describes a twist-grip throttle control in which a Bowden cable has its inner core attached to an axially adjustable anchor. The ends of the anchor are captured within a pair of helical grooves formed on the interior of a rotatable sleeve. Rotation of the sleeve causes the anchor and cable to be linearly moved parallel to the axis of rotation of the sleeve. Unfortunately, while devices of this type provided great strides in the art, the construction suffered from similar disadvantage as described with respect to U.S. Pat. No. 1,834,724.
U.S. Pat. No. 4,019,402 issued to the present inventor, describes a twist-grip throttle control unit in which a Bowden cable has its inner and outer members attached to pivot arms urged apart by a rotatable cam movable by the twist-grip. This construction, while offering distinct advantages for specific carburetors, requires a different cam means for various types of carburetors. Moreover, no means are provided for securely locking the outer member or sheath of the cable to the control unit housing. As will become clear in the descriptions hereinafter, the present invention presents novel and useful improvements in control mechanisms of those known in the art.
The present invention successfully overcomes the disadvantages of the known devices by providing a twist-grip cable control which has linear movement of the cable parallel to the axis of rotation of the twist-grip. Further, the inventive device provides a twist-grip control in which the amount of twist-grip rotation necessary to effect a given movement of the cable is minimized. In addition, the twist-grip control of the present invention provides for ready adjustability of the amount of cable "throw" or movement so that the control may be used with various styles and makes of carburetors. The twist-grip control also provides for a limit on the grip rotation in order to prevent cable stretching. Still another advantage of the present invention is the provision of a cable control which has a positive locking means for securing the outer cable of a Bowden cable to the control housing so that the inner core of the cable may be forcefully released by counter-rotation of the grip in the event that it becomes jammed or kinked. The device of the invention further provides a positive cable member locking feature which insures a moisture and dust-proof seal to prevent contaminants from entering the control housing.